The present invention relates to a method for preparing zinc-oligopeptides which can be easily absorbed by the human body. Also, the present invention is concerned with a beverage or food composition, which can easily provide zinc for the human body.
Loss of the mineral balance in the body has been found as one of the causes of adult diseases, which have recently been increasing in incidence. With growing older, the human body becomes poorer at absorbing minerals. Nowadays, a deluge of processed foods is becoming as one main cause of upsetting the mineral balance of the body because most of them contain materials inhibiting mineral absorption.
Of various minerals, zinc is involved particularly in the onset of diabetes mellitus, one of the most popular diseases today. In fact, not only adults, but also a surprising number of children suffer from the disease at present, which is believed to be attributed in part to the lack of zinc. In Oriental medicine, zinc is also described to have physiological activity associated with sugar control and vigor in the body. Deeply affected in diabetes mellitus patients, the blood sugar control of the body has direct influence on the energy production necessary for life. Although other physiological functions are active, abnormal regulation of blood sugar in the body, which means that the metabolic process of converting sugar into energy is in an abnormal state, lowers the immunity of the body to exogenous pathogens as well as latent viruses, resulting in the body falling ill.
In the body, zinc serves as an essential mineral in activating insulin, in addition to being involved in regenerating muscle tissues and nerve tissues. Abundant as it is in blood, insulin cannot exert its full effects in the absence of zinc. That is, insulin which is not associated with zinc is not beneficial to diabetics. A similar case can be found with amylase, which is unable to function as a saccharification catalyst unless it is associated with ionic calcium.
One of the most important physiological activities of zinc is to activate insulin into a form useful in the treatment of diabetes mellitus. In turn, the activated insulin is responsible, in great part, for the production of energy. In addition, zinc was found to inhibit the expression of mutant genes, thereby making a contribution to anticancer activity. Further, zinc is known to take part in a catalytic reaction necessary for DNA polymerization and therefore affect the rapid regeneration of injured tissue. In this regard, zinc has some connection with acceleration of wound healing, prevention of prostate problems and hair loss, and treatment of acne and rheumatoid arthritis.
Recently, sufficient intake of zinc has been reported to significantly decrease the incidence of disease in children. When their diets are supplemented with zinc, children are 40% less likely to be taken ill with pneumonia and 25% less likely to get diarrhea. As stated above, diabetes mellitus may be caused when dietary zinc is insufficient. When insulin is not activated, the body is significantly deprived of available sugar, leading to loss of vigor.
In order to be activated in association with zinc, the insulin must not be in a pro-insulin form, but in a functional form. Stoichiometrically, one molecule of functional insulin (molecular weight 6,615) associates with a zinc atom (atomic weight 65). Therefore, functional insulin must be associated with zinc at a weight ratio of approximately 1,000:1. In the medical world, globulin zinc I is used as an insulin formulation, which is generally for subcutaneous injection, for the purpose of zinc activation of insulin.
Occurrence of diabetes mellitus in children in recent times, which was rare in the past, is believed to be strongly affected by dietary lifestyles, but not heredity. Fried foods, which children usually like, contain a large quantity of fat that suppresses the activity of zinc. Also, a high intake of processed foods inhibits activities of calcium as well as zinc because of their high contents of phosphoric acid. Lipids and phosphates are known to actively inhibit the absorption of minerals irrespective of which form they have.
Naturally, living bodies have to supplement consumed or deficient materials by themselves. Hence, it is necessary that people exercise restraint in their ingestion of materials which inhibit such a natural supplementary function. The loss of the supplementary functions owing to ingestion of inhibitory materials causes a vicious cycle of deficiency. For instance, deficient dietary zinc lowers the activity of insulin, and unconsumed insulin causes a decrease or ceasing of the production of insulin in the pancreas. On the other hand, when insulin is actively consumed, it must be replaced, and thus insulin is more actively produced in the pancreas. This is demonstrated by the fact that athletes, who consume large energy, contain zinc at an amount 20 times as much as that of ordinary people. Zinc enables insulin to actively promote the metabolism of sugar in the body.
However, most of the mineral-enriched materials developed thus far, are poor in absorbability by the human body. Calmodulin, a calcium-chelated oligopeptide, was found in neurotic system of the human body, and to be absorbed easy as Calmodlin molecular structure by the small intestine.
Hinted by the structure of calmodulin, the intensive and thorough research on facilitating of the human body to absorb zinc, conducted by the present inventors, resulted in the finding that minerals are better absorbed by the body when they combine with organic materials, especially oligopeptides, rather than alone.
Therefore, it is an object of the present invention to provide a method for preparing a zinc-oligopeptide which can be easily absorbed by the body.
It is another object of the present invention to provide use of zinc-oligopeptide in foods.
In accordance with an aspect of the present invention, there is provided a method for preparing a zinc-oligopeptide easily absorbable by the body, comprising the steps of: proteolyzing a suspension of protein in deionized water at a neutral pH range in the presence of a protease to give a mixture of oligopeptides; chelating zinc ions with the oligopeptides to give a zinc-oligopeptide solution; concentrating the zinc-oligopeptide solution and drying the concentrate to a powder.
In accordance with another aspect of the present invention, there is provided a beverage comprising the zinc-oligopeptide, in combination with at least one ingredient selected from the group consisting of vitamin-C, vitamin-B1, vitamin-B2, fructose, xcex1-amylase decomposed starch and magnesium stearate.